1. Field of the Invention
The present invention relates to a node device in an optical transmission network as well as a label management method and program used in the same and, more particularly, to a method for managing labels (e.g., time slots and wavelengths) in an environment where a path that is set manually and a path that is set through an autonomous decentralized protocol coexist.
2. Description of the Related Art
In an optical transmission network, an operator manually sets a path (hereinafter, such a path will be referred to as “manually set path”). However, to achieve more efficient operation and more efficient use of network resources, it is regarded as a scheme of promise to set a path through an autonomous decentralized protocol (ADP) such as generalized multi-protocol label switching (GMPLS) or an automatically switched optical network (ASON). Hereinafter, such a path that is set through ADP will be referred to as “ADP set path”.
Here, setting a path (path setting) means reserving a time slot and/or a wavelength along the route of a path that is desired to be set. In this meaning, a timeslot and a wavelength are referred to as a label.
The manually set path has the disadvantage that path setting is complicated because the setting is performed through centralized control by a network management system (NMS), but has the advantage that a path can be set as intended by an operator.
On the other hand, the ADP set path has the advantages of easy path setting and good efficiency in the use of network resources because the setting is performed through autonomous decentralized processing. However, there is a drawback that it is difficult to set a path reflecting the intention of an operator.
In the light of the foregoing, it has been considered to take the respective advantages by allowing a manually set path and an ADP set path to coexist in an optical transmission network including SONET (Synchronous Optical NETwork)/SDH (Synchronous Digital Hierarchy) devices, wavelength division multiplexing (WDM) devices, and the like.
Incidentally, GMPLS is disclosed in Japanese Patent Application Unexamined Publication Nos. 2006-352297 and 2004-179894.
However, in the case where a manually set path and an ADP set path coexist, the problem is that there is no means for distinguishing between a label to be used for the manually set path and a label to be used for the ADP set path.
As a result, there arise a problem that labels in the network are consumed by an ADP set path and consequently a manually set path cannot be set, and a problem that, conversely, labels in the network are consumed by a manually set path and consequently an ADP set path cannot be set. These problems cannot be solved by the techniques disclosed in the above-mentioned Japanese Patent Application Unexamined Publication Nos. 2006-352297 and 2004-179894.